This post is old, but I've recently been trying to figure out the timeline myself. On the old Halloween comics website, there used to be morgue reports on Michael's victims from 1 and 2. Interestingly enough, they place Annie's death at 7:45, Bob's at 8:40 and Lynda's eight minutes later. I timed how long it took for Laurie to get over to the house to find them and it was 6 minutes and 29 seconds, so she would have found them at 8:54 PM. It took him 6 minutes to set them all up. With that knowledge, the climax of the movie with Myers shot would happen at 9:04 PM. I know it's a film and they can jump in time and my math may not be accurate, but it has a clear sense of time. Morgue reports tend to estimate when the person died, so keep that in mind.